Constant-pressure solid rectifier.



I G. W. PICKARD.

' CONSTANT PRESSURE SOLID RECTIFIER.

' APPLICATION FILED SEPT. 15. 1909.

1 ,257,526. Patented Feb. 26, 1918.

A nv tor: 'raen/mfW/n z'cr fclrard 'vAtty UNITED s'ra rns PATENT clarion.

GEEENLEAF WHITTIEB PICKARP, OF AMESBURY, MASSACHUSETTS, ASSIGNOIB I WIRELESS SPECIALTY APPARATUS COIMQPANY, OF NEW YORK, N. Y-,'A. CQIQPQRA- TION OF NEW YORK.

CONSTANT-PRESSURE SOLID RECTIFIER.

To all whom it may concern Be it known that I, GREENLEAF WHITTIER PICKARD, a citizen of the United States of America, and a resident of Amesbury, Mass, have; invented certain new and useful- Improveinents in Constant-Pressure Solid Rectifiers, the principles of which are set forth in the following specification and accompanyi'ngg drawing, which disclose the form of the invention; which I now consider to be the 'best of the various forms in which the principles; of the invention may be embod This. invention relates to improvements in-solid Ife CtlfierS of oscillating and alternating currents of electricity, having utility particularly with small currents, such for example, as those employed in radio telegraphy and telephony. The object of the invention is to increase the efliciency of solid rectifiers', with particular respect to use as oscillation receivers in radio telegra'phy or telephony, wherein the currents are extremely minute. v

The invention consists chiefly, among other things, of the constant pressure solid rectifier hereinafter claimed, and described in connection with the accompanying drawings which are fullscale and of which Figure 1 is a front elevation of a complete device "constituting one of the many possible embodimentsofth'e invention; Fig. 2, a. plan of, the same; Fig. '3, an end elevation Fig.4, a transverse section of the sliding sur-base' I; Fig. 5, a plan and transverse.

' section of contact-point carrier .8; Fig. 6, side and front elevations of counterwe ght 12; Fig. 7, side and front elevations of a heavy weight 14, and Fig. 8, side and front elevations of a light weight 13.

'Mos't of the solid rectifying substances are commercially operative only on a fracture or cleavagesurface, which is almost invariiihlylluneven, as distinguished from a flat or 'even surface, obtained as by grinding or polishing, Even whereporhons of a fracuse. face are'smuoth, the surfacc'receiving the ci r' cui trna lr ing conductor is uneven as a whole l leretofore the, two conductors, the rectifier and the circu t maker, (or two. reetifyii ig ;conductors) have been pressed to-. nether, btain. the. substantially nertect Specification of Letters Patent.

' phonic or coherer type, being the employment of greater pressure for a given material-sufficient to convert the contact from a microphonic or imperfect contact not permitting operation by oscillation-rectification 0r valve-action, into the kind of contact above-specified as necessary for such operation.

The spring-action, entirely suitable fordelicate adjustments to imperfection of con; tact, has been considered heretofore as one Patented Rob. 26, 1918. ApplicationfiledSeptember 15, 1909. Serial No. 517,771,

tirely satisfactory for solid rectifiers, when so essentially and vitally modified as above as to permit rectifyinga'ction, and it has been assumed that it permitted-optimum efliciency of the rectification properties .of

the respective rectifying solids. I have. discovered, however, that by the means substantially as disclosed herein, the rectifying 'efiis ciency of practiically'all solid rectifiers'can. be materially increased, not only as to'the ease of adjustment of the-minute good contact, but as to the actual apparent rectifying property of the material. This result seems to be due to the ability of the means which cooperates with the rectifyingmaterial, to bring out and utilize to the maximum the inherent property of said material asit ne er has been before by means of thevarious forms of spring contact.-

As a rcsultof this invention the actual hut previously hidden defects of the springcontact method of obtaining the good con-.

tact required for rectifying action, are nowmade apparent. In practice, adjustmentmust be made very quickly on account of" the exigencies of the rapidtelegraphy' customary with the present advanced state ofthe art, 'and the result is that, with the ve rious points of the rectifyingmaterial which.

are employed, and the various degrees of spring prcssure, thesame pressure is pra'c; tically never usedon-a given place of con? tact, and almost. never, in practice, is the optimum pressure employed. Furthermore,

an, adjustment to optimum pressi-i-re (mean-.- legbere erasure for optimum efimenox) at.

' a given contact will probably not be the optimum pressure for an other contact of a different elevation on t e uneven surface of the rectifying material. It follows that for a given adjustment there will be only a few surface contact points of high rectifying elliciency, and for another given ad ustment there will be only a few other such contact maximum efiiciency.

points, the result beingl that at no one time, and probably never, w1 1 an operator in practice have a large number of efiicient contacts from which to rapidly select in the rush of commercial business. A further and most important defect of the spring operated contact is that for a given adjustment the operator seldom. if ever, can use a contact of good contact pressure-producing maximum efliciency having been once obtained for a givenquality of a given rectifying material, that pressure is maintained'constant for that material of that quality, and is never varied by the operator, although he is free to select any desired point of contact on the material. And this means for revolutionizing this art of the good contact rectifying detector consists simply in substituting the action of gravity for the contact .spring heretofore employed. That is to say, the difference in effect between the action of the spring and the action of gravity, in a good contact rectifying device, is the measure .of the novelty of the broad invention, in that the spring necessarily causes a variation in pressure, by expansion or compression, for contact points of varying elevations, while the gravity, of a given mass, permits movement of the cooperating contact over the uneven surface of the rectifying conductor but always limits the contact pressure-to the amount determined by the adjustment or mass of the Weight, no more and no less. Therefore the optimum pressure for one contact point is new/$26 invention, nearly all mum efliciency, and the operative adjustment to any contact point is instantaneous, so that if necessary the contact may be changed in the midst of the reception of a message, in case of the previous contact be coming temporarily inoperative for any reason. I

In brief, the invention in its broadest asect comprises a contact operating by grav- 1ty to obtain good or substantially perfect electrical contact on the surface of a material possessing the property of rectification under the conditions now well known as the result of my investigations. The invention doesnot include 'microphonic contact detectors ofany kind and has no relation with such devices.

While the, invention is so simple that it is readily understood without a drawing, yet the drawings are appended toshow. the best form of device which I have so far used, the particular disclosed device being adapted not only for commercial use, but for accurate measurement work, and being less simple in construction than a device adapted wholly for commercial work. The rectifying conductor galen is particularly specified herem as one o the most marked cases of improvement by this invention. While I have found galena to have a high power of rectification, yet it is impracticable, as a commercial device, for use in present day service, with the prior spring ,or variable pressure contact, on account of low degree of stability and its great difliculty of adjustment, that is to say, a given contact point on the surface is liable to become inoperative, and a new adjustment requires a time so lon as to be out of the question for commercia busmess. But by means of the constant pressure contact of this invention, the-number of operative contact points is so greatly in creased, that-considering its high rectification power, the disadvantageous feature of instability of contact is more than offset.

The efliciency of the gravity contact is so great that in cases of some solid rectifiers, the efficiency of rectification is thereby increased even slightly in excess of that of oxid of zinc of my prior Patent No. 924,827 of June 15th, 1909.

Any of the solid rectifiers' having the customary uneven surface may be held in the metal cup C, Fig. 4 as by fusible metal F.

(If desired, any of said solid rectifiers may be employed in the device of In said Patent No. 924,827of June 15th, 1909. c I The shank of this cup is removablyiheld in brass part 1, Fig. 4, by screw 2. ard rubber part 3, Figs-4 and 1, con'tains brass part 1, and binding post 4, Figs. 4 and 1, extends through 3 into 1 to connect the 'solidirecti fier in cup C with one side of the circuit.

All the above apparatus rests on marble base B, Fig. 1,'but is not attached to as base,

mamas being left free to be moved around under the gravity contact-point. Base B is provided with soft rubber feet 5. The ravity contact point is carried at the right hand end of the aluminum beam' or Hal nce lever L mounted on brass standard Fig. 1,.so as to be forced by gravity down j n the uneven bone ts of the invention would be present even if the gravity contact were carried by a spring so light and elastic as not to prevent the effective action of the weight in permitting substantially constant contact pressure. I

In this disclosure balance lever L has socured to it a brass pin 7, Fig. 1, over which is slipped a brass holder 8, Fig. 5, for brass contact-point P. Any desired conducting mat-erlalfmay be used for P, such as any of the solid rectifiers, as bornite. Screws 10,

. furnished with cups C containing a given 11 hold 8 to 7, and P to 8 res ectively.

Balance lever L has a knif e-edge mounting on standard S, as shown. In this particular case the gravity effect is obtained by the lever and its appurtenances including 7, 8, P, 10 and 11,-but in substance the device is simply a gravity-acting contact. In -the case disclosed a brass counterweight 12, Figs. 6 and 1, is provided, this being about twice the weight of the point-holder 8, Fig. 5. In order that the device may be ope-rated with various samples of each of various rec- ,ti-fying solids, as for purposes of measurement,-etc., an adjustment is provided, consisting of varying weights 13, 14, Figs. 1, 6, 7 and 8, operating on lever L along the raduated scale which extends from the kni e-cdge support to the center of pin 7. WVeights 13 and 14 may be of 1 gram of aluminum and 10 grams of brass respectively. conducting lead 15, Fig. 1, preferably connects L and S in shunt to the knife-edge support, to insure good circuit connections. This lead 15 should be of fine copper wire to have minimum resilience.

Under the left end of beam L a brass standard 16 may be secured to base B, and provided with an adjustin screw 17 In devices intended exc usively for commercial use by telegraph operators it is recommended that no weight adjustment be permitted, provided'that the operators are solid rectifier of constant quality. The device should be then set to the pressure determined in the laboratory by a control instrument such as illustrated herewith, to be optimum for that standard material.

A great advantage of the invention is engage with contact point P; all as more that there is practically no' adjustment to the device. Itis always ready whenXis under contact point P with the proper predet'elk mined pressure. Normally there is nothing for the operator to do. In case'his testing buzzer ever shows that the device has for some reason become inoperatiye'as tothe particular surface point of in contact with P, it is permissible for him/to move holder 3 slightly to obtain a new surface ,c'ont'act point. That, however,will very seldom be required in case of proper selection'of rectifying material and proper predetermination of contact pressure. "But when it does occur, as it may in the midst of a message, it is'essentialthat the operator be able to instantly restore'complete operativ'eness;' and" that is certainly permitted in all cases for the first I time by this invention, by reason of the fact that the contact pressure 'is -automutically maintained constant irrespective of' the movements of holder 3 and of the consequent varying elevations of X thereby caused to ticularlv pointed out hereinbefore.

I claim:

1. The combination with a solid rectifier of the class described and a contact member therefor, said members being relatively adjustable in respect of making contact with each other at various points of the contactsurface of the rectifier, 0f means carrying one of said members and movably mounted on a hearing which permits the mass of said means and contact-member to exercise exelusive control of the contact-pressurebe-' tween the two contact-members.

2. The combination with a. solid rectifier of the class described, of a contact member cooperating therewith, said members being adjustable to various points of contact on pivotallv supporting one of said contactthe surface of the'rectifier, and means for members whereby it is free to be'pressed against the other contact member exclusively by means of the weightof its Support and of itself.

'3. The combination with a mass of recti fying material having an uneven operating Contact surface, of a Contact member 00-. operating therewith. means for changing the location of the rectifying material to. bring different parts ofits surface into contact with the contact member, and means for movahly supporting the contact member whereby it is free tobe pressed exclusively by the weight of its support and of itself into a contact of operative pressure with the rectifving material.

4. The combination "with a mass of rectifying material of the class described. and having an uneven operatingcontact surface, of a contact member coiiperating therewith. and means for freely supporting said con- "'tact member near the rectifying material 'whereby its contact-pressure-ttherewith is contact member being relatively movable for the selection of various contact points on the surface of'thc former; and meanscontrolled exclusively by gravity for obtaining uniform contact-pressure between the contact member and the various contact points on the uneven contact surface of the rectifying material. l

7. In a device of the character described,

a base or support, a contact disk mounted upon said support, a contact cup provided with an uneven contact surface rotarily mounted on said disk and an oscillatory weighted beam bearing a' member cotiperating therewith. a

8. In a device of thecharacter described,

means for supporting a pair of cooperating contacts, one of said contacts having an unoven operating surface and one of said 0011- tacts controlled by a weighted beam.

GREENLEAF WHITTIER PICKARD.

Witnesses:

Nanun M. A'r'rnrncn, Jacoa T. Cnoarn. 

